System of control.



H. A. STE-EN.

SYSTEM OF CONTROL.

APPLIUATION FILED JULY 24, 1911.

1,031,096. Patented July 2,1912.

UNITED STATES PATENT OFFICE.-

HALFDAN A. STEEN, F MILWAUKEE, WISCONSIN, ASSIGNOR TO. ALLIS -CHALMERSCOMPANY, A CORPORATION OF NEW JERSEY.

Specification of Letters Patent.

SYSTEM OF CONTROL.

Patented July 2, 1912.

Application filed July 24, 1911. Serial No. 640,342.

To all whom it may concern:

Be it known that I, HALFDAN A. STEEN,

subject of the King of Norway, residing at controllers.

In the operation of switches in electric circuits there is always moreor less arcing at the contacts where the circuits are finally broken.Arcing to a small degree at contacts which are comparativelylarge, causelittle trouble, especially when such contacts are readily accessible to.render the trimming of-such contacts a simple matter. But

when contacts are made of a single strip of thin metal as is the casewith indicatorpointers which form movable contact members of switches inelectrical circuits, a single occurrence of arcing may render suchcontacts useless. Bourdon gages, used in fluid pressure systems, havesuch indicators which act asmovable contacts of switches for making andbreaking electric circuits.

It is the object of this invention to prevent arcing at the contacts ofgages and other similar switches which have limited current carryingcapacity. This object is accomplished by providing automaticallyactuated auxiliaryswitches controlled by opposed windings forestablishing a shunt around the frail contacts before the circuit itbroken at such frail contacts under certain conditions, the arcingoccurring at the auxiliary switches under all conditions.

The invention is illustrated diagrammatically on the accompanying sheetof draw- The various novel features of my invention will be apparentfrom the description and drawing and will be particularly pointed out inthe appended claims.

Among some instances where my invention is of commercialvalue, usefulapplication is found in fluid pressure systems wherein a gage is usedwhich indicates the rise and fall of fluid pressure and which acts as adouble throw switch, the movable member of which makes and breakscertain circuits for controlling a main circuit controller, which'inturn controls the supply of current to a motor for operating a fluidsupplying pump. 1

A motor 10, here shown as being shunt wound, receives its supply ofenergy from mains. 11 and 12 through intermediate conductors l3 and 14and the main switch 15 of a circuit controller 16. The motor is adaptedto operate a pump 17 for supplying compressed air to a reservoir 18,from which compressed air is transmitted through a pipe 19 to a pressuregage 20. The compressed air entering the gage passes into a resilientcurved tube 21, which moves in opposite directions depending upon therise or fall of fluid pressure. The pressure indicator or movablecontact member 22 is secured to and moves with said tube 21. As thepressure in the reservoir 18 rises and falls, the movable contact member22 of the gage is shifted from one position to another alternatelyengaging stationary contacts 23 and 24 of said gage. When the movablecontact member 22 engages the stationary contact 23, a circuit iscompleted from main 11, through conductor 25', movable contact member22, contact 23, solenoid 26, conductor 14, to the other main 12. Uponthe completion of said circuit, the core 27 of the circuit controller 16is raised due to the action of the current in coil 26, and a shuntcircuit around the gage or double throw switch is formed from conductor25, through conductor 28, bridging contact 29 of an aux iliary switch 29to conductor 30. At the same time another auxiliary switch 31 having abridging contact 31 is closed, and

which, upon a movement of the contact member 22 to the stationarycontact 24, will establish a circuit through a coil or winding 32 whichacts in opposition to the winding 26. When the circuit is formed throughthe winding 32, the flux set up thus acts in opposition and overcomesthe-flux set up by the current in the winding 26, whereupon the mainswitch 15 of the circuit controller is opened. In other words the coil32 is a ing in value. As the pressure gradually decreases, with thefluid escaping through the exhaust 35 of the reservoir 18, the movablecontact member 22 moves to the left due to the decrease in pressurewithin the resilient tube 21. When the pressure has reached a minimumvalue of the operating range, the movable contact member 22 engages thestationary contact 23 of the gage, completing thecircuit from main 11through conductor 25, movable contact member 22, contact 23, winding 26,conductor 14, to the other main 12. The coil 26 thus being energized,the core 27 is drawn up, closing the main switch 15 of the circuitcont-roller l6, whereupon the motor 10 is connected to the mains l1 and12. The motor immediately operates the pump and the fluid pressure isgradually raised, causing a gradual movement of the movable contactmember 22 of the gage from the stationary contact 23 toward stationarycontact 24. When the movable contact member 22 leaves the stationarycontact 23 no sparking is produced at said contact for the reason thatat the instant the circuit controller is operated, closing switch 15,the two auxiliary switches 29 and 31 are also closed by the circuitcontroller, a shunt around the gage switch being thus completed fromconductor 25 through conductor 28, auxiliary switch 29' to conductor30.- As the motor continues operating the pump, raising the fluidpressure, the movable contact member 22 is gradually shifted farther tothe right due to the action of the fluld pressure in the resilienttube'21. The pressure of the fluid increases until the movable contactmember 22 comes into engagement with the stationary contact 24 of thegage switch, when a circuit is formed from main 11, through conductor25, movable contact 22, contact 24, auxiliary switch 31, winding 32,conductor 14 to the other main 12. Due to the fact that the windings '26and 32 are opposed to eachv other, the

fluxes, set up by the current in said wind-- ings, are neutrallzed,causing the main switch 15 of the circuit controller to be opened, thuscutting off the motor from its pump to stop immediately. At the sametime the main switch 15 of the circuit controller is opened, both of theauxiliary switches 29f and 31 are opened and what arcing there is totake place, occurs at the switches 15, 29 and '31. It is, therefore,seen that when the fluid pressure again decreases in value and themovable contact member 22 leaves the contact 24, no live circuit isbroken and, therefore, no arcing takes place at said contacts. Due tothe an rangement of the opposing coils and the circuits including theshunt circuit around the pressure gage, all arcing at the pressure gagecontacts is obviated.

There may be other arrangements and modifications of the system which Ihave here shown and described, and I intend to cover all sucharrangements and modifications which do not involve a departure from thespirit and scope of my invention as set forth in the appended claims.

- What I claim as new is:

1. In combination, .a circuit controller, two opposed windingscontrolling said c0ntroller, a double-throw switch which in its twopositions is in series with said two windings respectively, and twoauxiliary switches operated by said controller, one of said auxiliaryswitches being in shunt to the doublethrow switch in one posit-ion, andthe other being in series with said double-throw switch in the otherposition. a

2. In combination, a circuit controller, 0pposed windings controllingsaid controller, a double-throw switch which in its two positions is inseries with diiferent ones of said. windings, and two auxiliary switchesoperated by said controller, one of said auxiliary switches being inshunt to the doublethrow switch in one posit-ion, and the other being inseries with said double-throw switch in the other position.

3. In combination, 'a circuit controller, a winding adapted to control.the movement of said controller in one direction, another windingadapted to influence the movement of said controller in a differentdirection, a double-throw switch which in its two positions is in serieswith said different windings respectively, and a plurality of auxilandthe other being in series with said first switch in another position.

5. In a pressure control system, the com- Milwaukee, Wis, July 7, 1911.

bination of a circuit controller, opposed In testimony whereof I afli xmy signala windings controllin said controller, a ture, in the presenceof two witnesses.

switch which in di erent ositions is in series with said windings respectively, and HALFDAN E a plurality of auxiliary switches, one ofWVitnesses:

which is in shunt to said first-mentioned CHAS. L. BYRON, 1.0 switch inone position, and another of which G. B. ScHLEY.

is in series with said first-mentioned switch in another position.

